Air brake control valve



D. F. SEARLE AIR BRAKE CONTROL VALVE Dec. 8, 1936.

A Filed Jn. 2, 1955 2 sheets-sheet 1 F i G.

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lNvl-:NroR: DUDLEY Ff( SEAR E ATToRNEYi Dec. 8, 1936. D. F. sEARLE AIR BRAKE CONTROL VALVE Filed Jan. 2, 1935 2 Sheets-Sheet 2 FIG; 3f

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DUDLEY F. SEARLE. l mi ATTORNEY Patented Dec. 8, 1936 UNITED STATES AIR BRAKE CONTROL VALVE Dudley F. Searle, Oakland, Calif. y

Application January 2, 1935, Serial No. 63

3 Claims.

This invention relates to improvements in air brake control valves and more particularlyy to con.- trol valves for vacuum power booster brakes.

- Among the objects of this invention is to facili- 151 tate' smooth application of the brakes.

Another object is to increase the sensitivity of the brake kcontrol.

Another object is to render a single disk type N control' valve capable of having both its atmos- 10 pheric and vacuum power ports closed to the brake power chamber.

' Another object is to provide a valve at minimum expense that is permanently reliable in operation.

Other objects and advantages scription progresses. f

In 'this specification and the accompanying drawings, the invention is disclosed in its prelferred form. It is, however, to be understood that it isnot limited to this specific form because it rmay be embodied in other forms within the lspirit of the invention as defined by the claims following the descrtiption. .e

In the two sheets of drawings:

Fig. l is a diagrammatic side elevation showing a control valve constructed in accordance with thisr invention installed in a suction power booster brake system.

Fig. 2 is a longitudinal lsection of the control valve in inoperative position with the atmospheric port open to the brake power chamber.

`Fig. 3 isa similar View of the same with the vacuum suction port open,

Fig. l is'a similar View of the same with a slight- 1y' modiiied valve disk with both atmospheric and suction ports closed. l Y

`In detail the construction illustrated in the drawings, referring more particularly to Fig. 2, comprises the valve body I having the Vcentral `recess 2 surrounded by the annular valve seat 3. The port 4 ccnnnunicates with the recess 2 and has the elbow pipe joint 6 screwed thereinto whichleads oi to the brake power chamber. The port 'I opens to the interior of the body I but is separated from the-recess 2 by the valve seat 3. The elbow 8 is screwed into the passage I and is connected by the flexible hose 9 to a suitable source 'of subatmospheric air pressure such as the intake manifold I of an internal combustion engine.

The lbody I has the annular shoulder II surrounded by the flange I2. The cover I3 is securedr to the ilange I2 by the screws I4. The resilient valve disk I5 has its perimeter clamped between the cover I3 and the annular shoulder II.

l5 appear as this de- (Cl. 294-54) y.

The valve disk, may be fabricated of rubber vulcanized on tothe thinspring metal plate I6 as in Fig. 2 and Fig. 3 or it maybe formed of plain rubber as in Fig. 4. When the valve is'n the inoperative position the valve disk I5 firmly seats itself at 3 byits own resiliency. A The suction port 'IV is thus cut offfromcommunication withV the power chamber port 4. Y The cover I3 is-recessed at IIopposite the valve disk' I5 and has the atmospheric ports I8'therethrough.' The valve disk'ihas the central opening I9. When the valve is in the-inoperative position as in Fig. 2, the atmospheric ports I8 communicate with the power chamberpport 4 through the opening I9. u f v Y The valve bodyf I has the lug` with the threaded shank 2I screwed thereinto which is adaptedto be attached to a suitablecross member or bracket 22, see Fig. 1. -bythe nut 23 to mount thevalve. 'I'he valve stem24 extendsthrough 20 the boss 25 on, the cover I3 and is slidable therein and passes through the opening IIJ-inthe valve disk I5. The plunger head 26 is xed on the end of the stem 24 by means of thetaper pin 21 and is adapted to engage and operate the valve disk "25 I5. The spring 28 encircles the stem 24 and expands between thev cover I3 and the plunger 2G to normally urge the plunger away from the valve disk I5 toward the bottom of the recess 2. The sleeve 29 on the stem 24 limits the movement of the p1unger 26y toward thecover I3.

The power brake. installation may be any one of the several types commercially available. In the present instance it includes the0 brake power .chamber 30, see Fig. l, mounted on the` cross Tg5 member 3| and divided into two compartments by the flexible diaphragm 32 therein. The lhose 33 is connected to one side of the chamber 3D .and leads olf to theelbow joint 6 of the control valve. The opposite sidejof the chamber uninterruptedly communicates with the atmosphere through the portv 34. The cross shaft 35 has the lever 36 thereon intermediate its length` connected tothe diaphragm 32 by the rod 3l. The cross shaft has vertical levers at each end, to the topy and 45 bottom of which are connected the brake pull rods 38 and 39 which operate the brakes on the front and rear wheels respectively. The spring 40 normally maintains the brakes released and draws the diaphragm 32 toward the atmospheric port 34. v y

The conventional brake pedal 4I is mounted on the usual shaft 42 and has the arm 43 projecting therefrom. The spring 44 urges the brake pedal into inoperative position. The floating lever 45 has the longitudinal slot 46 therein which engages the pin 41 on the arm 43. The clevis 41 is mounted on the end of the valve stem 24 and is connected to the bottom of the lever 45. A similar clevis 48 pivots on the top of the lever 45 and is operatively connected to the lever arm 49 depending from the cross shaft 35 by the link 50.

The apparatus operates substantially as follows: Operation of the pedal 4I moves the pin 4l laterally. The operative movement of the brake system checks the movement of the link 5U, The floating lever 45 accordingly pivots on the clevis 48 and pulls the valve stem 24. The movement of the stem 24 engages the plunger 26 against the valve disk l5 and closes the opening I9=there through. This cuts off the port 4 leading tothe power chamber through the hose 33 Vfrom communication with the atmosphere. Y .l f

The continued movement of the plunger pushes the resilient valve disk I5 into the recess I'I away from the seat 3 as shown in Fig. 3. The valve disk I5 is not freely flexible but is of moderate resiliency so that the force exerted by the plunger 26 at the center of the disk will move the body of the disk sufficiently to disengage it from the seat 3. The sleeve 29 limits further movement of the plunger 26 and obviates pinching the rubber disk I5 against the cover I3. Communication is thus provided between the ports I and 4 past the valve seat 3. Y

The subatmospheric pressure in the intake I of the internal combustion engine then partially evacuates the power chamber 30 through the hose 33, the ports 4 and 'I and the hose 9. Theatmospheric pressure reacting against the opposite side of the diaphragm 32 in the `power chamber urges the diaphragm toward the partially evacuated compartment. This retracts the rod 3l and the lever 3G to partially rotate the cross shaft 35. The rods 38 and 39 are thus drawn up to progressively apply the vehicle brakes.

Thepartial rotation of the cross shaft 35 swings the lever arm 49 and advances the link 5U Vtoward the floating lever 45. This swings the floating lever on the pin 4l and moves the valve stem 24 and the plunger 26 thereon laterally toward the bottom of the recess 2. The inherent elasticityof the valve disk I5 causes it to accompany the movement of the plunger 24. The disk I5 is sufciently flexible so that the atmospheric pressure against its side opposite the seat 3 will cause the portion intermediate its margin and the lplunger 23 to yield and bulge toward the seat 3 until it rmly engages it. The plunger 26is still in engagement with the disk and holding the opening I9 closed, as in Fig. 4.

`When this occurs the power chamber port 4 is cut off from both the suction port 'l andthe atmospheric ports I8. This stabilizes the -air pressure in the chamber 30. The tension of the spring 48 and the mechanical resistance of the brake system then balances the operative eiect of the subatmospheric pressure in the' chamber 30. -The brakes may be held continuously applied to the extent desired for a prolonged period without variation in the -braking effect.

This is an important feature of the present invention. In prior single disk control Vvalves it was impossible to maintain both the vacuum and the atmospheric ports continuously closed to the power chamber. Thus when the brakes were partially applied, the pressure in the power chamber was necessarily being either raised or lowered with consequent variationsV in the braking eiect.

The operation of the valve as thus described renders it largely self balancing since as the fluid pressure differential on the two sides of the disk I5 increases, the disk yields and bulges intermediate its margins and the plunger 23. This seats the disk at 3 without appreciable reactionary movement of stem 24. This is important, as when the brakes near full application great variations of braking pressure are possible with very slight movement of the linkage mechanism.

When the valve is in the position shown in Fig. 4 with both the suction port 'I and the atjmospheric ports I8 closed, the brakes can be still further applied by further pressure on the pedal 4I. The link 50 being held stationary by the resistance of the brake system, the lateral movement of the pin 41 causes the floating lever 45 to pivot on the clevis 48 and operatively pull the stem 24. The plunger 26 then again unseats the valve disk I5 as shown in Fig. 3. The motor intake I0 then further evacuates the power chamber 30 through the uncovered port 'I thus further applying the brakes. In this vmanner an extremely sensitive control of the application of the brakes is secured, regulated by the pressure on the pedal 4I. Release of the pedal 4I swings the floating lever 45 on the clevis 48 and pushes the valve stem 24 inward until the plunger abuts the bottom of the recess 2. The spring `28 expedites this movement of the plunger. The opening I9 being left uncovered, as in Fig. 2, air flows through the ports I8, the opening I9, and the `port 4 to restore atmospheric pressure in the power chamber 30. The spring 40 then restores the brake system to the inoperative condition.

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is:

1. AnV air brake system including a control valve comprising a body; a resilient disk having its, margins coniined in said body and having a central opening therethrough; a stem extending into said body; a plunger head on said stem and adapted to engage said disk and close said opening therethrough; said body having an annular valve seat therein surrounding said plunger and adapted to be engaged by said disk; said body also having ports inside and outside the circumference of said seat and adapted to communicate with a power chamber and a source of sub-atmospheric air pressure respectively; the side of said disk opposite to said seat and plunger being exposed to atmospheric pressure at all times; said plunger being adapted to displace said disk from said seat.

2. An` air brake system including a control valve comprising a body having a recess therein; a resilient disk having its margins conned in said body and having a central opening therethrough; a movable operating stem extending into said body; a plunger head on said stem and adapted to engage said disk and close said opening therethrough; said body having an annular valve seat therein surrounding said plunger and adapted to be engaged by said disk; said body also having ports inside and outside the circumference of said seat and adapted to communicate with a power chamber and a source of subatmospheric air pressure respectively; the side ofY said disk opposite to said seat and plunger being exposed to atmospheric pressure at all times; said disk being relatively stiiT so that the movements of said plunger will displace the body of said disk sufliciently to disengage the disk from said seat; and resilient means urging said also having ports inside and outside the circumference of said seat and adapted to communicate with a power chamber and a source of sub-atmospheric air pressure respectively; the side of said disk opposite to said seat being exposed to 5 atmospheric pressure at all times; said plunger being adapted to displace said disk from said seat; the resiliency of said disk permitting it to yield under the atmospheric pressure exerted thereagainst when the fluid pressure differential l0 on its opposite sides becomes sufliciently great.

DUDLEY F. SEARLE. 

